Why Do Most of the Flowers in a Temperate Deciduous

Why do most of the flowers in a temperate deciduous forest bloom in the spring?

A) Most of the rain falls in the spring.
B) The leaves of deciduous trees do not block the light in the spring.
C) The largest number of insect pollinators are available in the spring.
D) Nutrients are most available in the spring.
E) In the spring the trees do not block the wind and thus prevent wind pollination.